1. Field of the Invention
The invention relates to transmissions in an uplink channel in a communication system, and particularly but not exclusively, to an enhanced dedicated channel in a UMTS system.
2. Description of the Related Art
A mobile communication system is an example of a system in which an access network is provided to allow access to the system functionality for user terminals.
In a universal mobile telecommunications system (UMTS), a radio access network typically provides access for user equipment to a mobile communications system core network. The user equipment typically communicates with the access network over a radio interface, the access network including a plurality of Node Bs, or more generally network access points, with which the user equipment establishes a connection. Each of the Node Bs is connected to one or more radio network controllers, or more generally network access controllers.
A dedicated channel (DCH) is provided in a UMTS system for uplink traffic from the user equipment to the radio network controller via the Node B. A frame transmission interval is defined for this channel. A typical and thus far the shortest frame transmission interval for dedicated channel is 10 ms.
In 3rd Generation Partnership Project, Technical Specification Group Radio Access Network (3GPP TSG-RAN) there has been proposed high speed uplink packet access, also known in 3GPP as Frequency Division Duplex (FDD) Enhanced Uplink, including an enhanced DCH, E-DCH. This proposal is documented in 3GPP TR25.896.
A proposed functionality of the E-DCH is a hybrid automatic repeat request (H-ARQ) error detection correction mechanism. This error control mechanism is proposed to be implemented in the Node B for uplink packets.
A further proposed characteristic of the E-DCH is to provide a shorter frame transmission interval of 2 ms.
A still further proposed functionality of the E-DCH is to support soft handover (SHO).